The non-prepublished International application PCT/EP2007/063348 entitled “Peptides capable of binding to serum proteins” describes methods for generating peptides that are capable of binding to serum proteins, which peptides can be linked or fused to a therapeutic moiety, compound, protein or other therapeutic entity in order to increase the half-life thereof.
PCT/EP2007/063348 also describes a number of specific amino acid sequences that are capable of binding to human serum albumin and that can be linked or fused to a therapeutic moiety, compound, protein or other therapeutic entity in order to increase the half-life thereof. These amino acid sequences include the amino acid sequence AASYSDYDVFGGGTDFGP (SEQ ID NO:1), which is called “17D12” in PCT/EP2007/063348 and which is listed in PCT/EP2007/063348 as SEQ ID NO:3.
It is an object of the present invention to provide amino acid sequences with improved binding to serum albumin, compared to the amino acid sequence AASYSDYDVFGGGTDFGP (SEQ ID NO:1). In particular, it is an object of the invention to provide amino acid sequences that:                bind better (as defined herein) to human serum albumin than the amino acid sequence        
AASYSDYDVFGGGTDFGP,(SEQ ID NO: 1)and/or                can specifically bind (as defined herein) to human serum albumin and that can also specifically bind serum albumin from at least one other species of mammal (such as serum albumin from a mouse, rat, rabbit, dog or a species of primate such as baboon or rhesus monkey), and in particular can specifically bind to human serum albumin and to serum albumin from cynomolgus monkey;and/or        can bind to (human) serum albumin and that have other improved properties for pharmaceutical use compared to the amino acid sequence AASYSDYDVFGGGTDFGP (SEQ ID NO:1), such as improved stability, improved protease resistance, etc.;and/or        when linked or fused to a therapeutic moiety, compound, protein or other therapeutic entity provide a greater increase of the serum half-life or other pharmacologically relevant properties than the amino acid sequence of SEQ ID NO:1 (when linked or fused to the same therapeutic).        
It is also an object of the invention to provide amino acid sequences that can be linked or fused to a therapeutic moiety, compound, protein or other therapeutic entity, such that the resulting compound or construct has an improved half-life compared to a corresponding compound or construct that contains the amino acid sequence AASYSDYDVFGGGTDFGP (SEQ ID NO:1).